Processing a portion of a high pressure gas stream

ABSTRACT

A METHOD FOR PROCESSING A PORTION OF GAS FROM A HIGH PRESSURE RICH GAS STREAM WHEREIN LIQUIDS ARE REMOVED FROM THE GAS, ADSORBERS ARE REGENERATED WITH PROCESSED HEATED GAS, AND REMOVED LIQUIDS ARE REINJECTED INTO THE HIGH PRESSURE RICH GAS STREAM.

Aug.. 17, 1971 J. E. SCHNEIDER PROCESSINGA PORTION OF A HIGH PRESSURE GAS STREAM Filed pril 25, 1969 2 Sheets-Sheet 1 Aug. 17, 1971 J. E. SCHNEIDER PROCESSING'A PORTION OF A HIGH PRESSURE GAS STREAM Filed April 25, 1969 2 Sheets-Sheet 2 A T TORNEVS United State US. Cl. 203-340 9 Claims ABSTRACT F THE DESCLSUIRE A method for processing a portion of gas from a high pressure rich gas stream wherein liquids are removed from the gas, adsorbers are regenerated with processed heated gas, and removed liquids are reinjected into the high pressure rich gas stream.

This invention relates to processing gas. Another aspect of this invention relates to processing a portion of a highpressure rich gas stream.

In processing rich gas streams to remove a portion of the higher boiling components therefrom, large amounts of costly equipment and power is generally required. Most processing facilities are also permanent installations usually located at the terminal or branch terminal of a high pressure rich gas pipeline. At such facilities, all the high pressure gas stream is passed through the processing apparatus, lean gas is delivered into large sales lines, and the removed Valuable higher boiling components are transported to other nearby facilities for sales or further processing.

Lean gas discharged into the high pressure sales lines is thereafter sometimes often transported several hundreds of miles to locations near the high-pressure rich gas pipeline. Such transportation of lean gas requires utilization of large amounts of equipment and labor. At other times, lean gas is needed at locations near a high-pressure rich gas stream, but remote to a lean gas supply source, for emergency situations or other needs of short duration. In these situations, the installation of a lean gas supply pipeline is not practical and the construction of a permanent processing plant to supply the limited needs is not only prohibitive in regard to equipment and labor expenditures, but in addition, creates additional expenditures of equipment and labor to transport recovered liquids to liquid processing facilities or sales outlets.

It is therefore an object of this invention to provide a method for procesing relatively small amounts of gas from a high-pressure rich gas stream. Another object of this invention is to provide a method for processing relatively small amounts of gas from a high-pressure rich gas stream that is remotely located relative to a lean gas supply source. A further Object of this invention is to provide a method for processing gas, as previously described, with reduced equipment, labor, and power requirements. A still further object of this invention is to provide a method for processing gas, as previously described, which is relatively quickly placed into operation and removed from use. Further objects and advantages of this invention will become apparent to those skilled in the art from the following discussion, appended claims, and accompanying drawing.

A more complete understanding of the invention may be utilized by reference to the accompanying schematic drawing of which FIG. 1 shows the equipment and liuid ow paths utilized in the process of this invention and FIG. 2 shows absorber switching equipment utilized in the process of this invention.

Referring to FIG. 1, a portion of the rich gas, containing methane, ethane, propane, butane and some higher boiling hydrocarbons, flowing through the high-pressure, rich gas pipeline 2, passes through line 4 and into a first liquid knock-out 6 where entrained liquid is removed from the gas. The removed liquids settle in the knock-out 6, are discharged therefrom through first liquid discharge line 8, and are thereafter reinjected into the high-pressure rich gas stream. The gas, being lighter than the liquid, rises to the upper portion of the knock-out 6 and is discharged through gas discharge line it). A regulating valve 12 and pressure controller 14 are positioned within the gas stream iiowing through line ll() to regulate the liow rate of gas discharged from the high-pressure, rich gas line 2.

Downstream from the regulating valve 12, the gas stream is separated for further processing into first and second gas streams 16, 18. The first gas stream 16 passes into a second liquid knock-out 20 where additional entrained liquid can be removed. The removed liquid is discharged from the second liquid knock-out 20, flows through second liquid discharge line 2?., and is thereafter reinjected into the high-pressure rich gas stream.

Although the method of this invention will function properly if the rich gas stram is passed through only one liquid knock-out, it has been found that the efficiency of the process is increased and the compressor is better protected from entrained liquid if a second liquid knock-out is employed to remove entrained liquid therefrom.

Gas discharging from the second liquid knock-out flows through line 24 to a compressor 26 where the pressure of the first gas stream is elevated to a pressure 30 p.s.i., preferably within a range from 20 p.s.i. to 50 p.s.i. greater than the pressure in line 2. The pressure of the first gas stream is increased to enable said stream to flow through subsequent processing equipment yand thereafter be reinjected into the high-pressure rich gas stream. The rst gas stream is then passed through a gas-gas heat exchanger 28 for preheating.

After passing through the regulating valve 12, the second gas stream iiows through a first adsorber 29 wherein the wet second gas stream is in contact with charcoal, or other like adsorbing material. Higher boiling compounds are adsorbed from the rich gas stream by the charcoal and the resultant lean gas stream is discharged into line 30.

It is necessary to periodically remove the liquids that have been adsorbed by the charcoal from the gas. In the regeneration of a charcoal bed, heat is utilized to vaporize and remove the adsorbed liquids. Thereafter, the hot regenerated adsorption material must be cooled. In this invention, the lean second gas stream flowing through line 30 is discharged into a hot, regenerated second adsorption column 32 for cooling the charcoal contained therein and conditioning said column for further gas drying functions. Of the higher boiling components contained in the rich gas stream, approximately percent of the propane and all of the butane and higher fractions are removed.

The heated second gas stream discharging from the second adsorber 32 liows through line 3d and into the gasgas heat exchanger 28 wherein the hot second gas stream is utilized to preheat the first gas stream. After passing through the heat exchanger 28, the lean, cooled, first gas stream flows from the process system through sales line 36, and is thereafter delivered to consumers of lean gas.

The heated first gas stream discharging from the heat exchanger 28 flows into heater 38 where the temperature of said stream is elevated to a temperature above 600 F. and preferably to a temperature in the range of 55() to 650 F. In order to simplify the process of this invention, a portion of the lean second gas stream discharging from the heat exchanger 28 through sales line 36 is delivered hy line dd to supply fuel for the heater 3l.

The heated first gas stream discharging from the heater 38 is thereafter uniquely utilized in this invention as the regenerating medium for the liquid-charged third adsorption column. Use of the available heated gas for the regeneration medium avoids the necessity of equipping this processing system with steam generators, water reservoirs, fresh water, condensers, and other regeneration equipment and supplies. Labor expenditures for maintaining in an opera-ble condition this heretofore used equipment is avoided in this invention. It is also unnecessary to separate the desorbent gas from the desorbed components.

The heated, second gas stream flows from the heat exchanger 28, through line 40, and into and through the third adsorption column 42. The heated first gas stream passes through the third adsorber 42 in contact with the liquid-charged charcoal contained therein. The temperature of the third adsorber is elevated by the first gas stream to a level wherein the adsorbed liquid within the charcoal is vaporized and removed therefrom. The first gas stream and removed liquid are thereafter discharged from the third adsorber and reinjected into the high-pressure wet gas stream.

FIG. 2 shows a conventional header arrangement which enables the first and second streams to be systematically redirected through the adsorbers 29, 32 and 42. By proper manipulation of the switching valves of the header, the now rst adsorption column 29, after it becomes liquid charged, can be caused to replace the third column 42 and be regenerated by the hot first gas stream, the now hot regenerated third column 42, can be caused to replace the second column 32 and be cooled by the second gas stream, and the noW cooled second column 32 can be caused to replace the first column 29 and be utilized for exacting the higher boiling components from the second gas stream. Periodically re-routing the first and second gas streams permits the first adsorption colunm 29 to be constantly maintained in an operable condition.

In order to more easily transport the equipment of this invention to sites adjacent the high-pressure rich gas pipeline, it is preferred that all equipment and piping be mounted on one or more I-beams or similarly constructed conventional skids. Transportation of the process plant can then be accomplished by trucks or rail cars. At the location the equipment can thereafter be easily connected to the pipeline and rapidly placed in operation.

By reinjecting removed liquids into the high-pressure rich gas stream, the remotely located processing method of this invention avoids labor and equipment expenditures for transporting, processing, or selling said liquids. By uniquely utilizing a portion of the gas stream as a regenerating medium for the adsorption column, the processing method of this invention also avoids the utilization of condensers and other like equipment heretofore employed in a regeneration loop and adsorption type processing plant. Mounting of the equipment of this invention on a conventional portable skid and avoiding the use of a plurality of power sources and other generally employed equipment, enables the process method of this invention to quickly and easily supply lean gas at sometimes remote locations.

Various modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion and accompanying drawing, and it should be understood that this invention is not to be unduly limited thereto.

That which is claimed is:

1. A method for processing a portion of gas passing through a high pressure line, comprising:

extracting a portion of gas from a high-pressure rich gas stream;

separating the extracted gas into first and second streams;

increasing the pressure of the first gas stream;

passing the first gas stream through a gas-gas heat exchanger;

extracting liquid from the second gas stream by passing said stream through a cooled, regenerated first adsorber;

cooling a hot, regenerated second adsorber by passing the lean, second gas stream therethrough;

passing the lean, second gas stream through the heat exchanger to preheat the first gas stream;

delivering the lean, second gas stream into a sales line;

heating the first gas stream;

injecting the hot, first gas stream into a liquid-charged third adsorber;

regenerating the liquid-charged third adsorber by contacting the liquid within the adsorber with the hot, first gas stream;

forcing the liquid and the first gas stream from the adsorber; and

reinjecting the liquid removed from the third adsorber and the first gas stream into the high-pressure, rich gas stream.

2. A method, as set forth in claim 1, including discharging a portion of the lean second gas stream from the heat exchanger into the heater for fuel.

3. A method, as set forth in claim 1, including removing entrained liquids from the total gas stream discharging from the high-pressure, rich gas stream.

4. A method, as set forth in claim 1, including extracting liquids from the second gas stream by passing said stream over charcoal contained in the adsorber.

5. A method, as set forth in claim 1, including rotating the position of the adsorbers in the gas streams when the first adsorber has been liquid charged, the second adsorber has been cooled, and the third adsorber has been regenerated.

6. A method, as set forth in claim 1, including providing process equipment of claim 4 that is skid mounted, moving the skid mounted processing apparatus adjacent the high pressure rich gas stream; connecting the processing apparatus to said stream; processing gas as needed; and disconnecting the processing apparatus from said stream.

7. A method, as set forth in claim 1, including extracting entrained liquids by passing the rich gas streams through a liquid knock-out.

8. A method, as set forth in claim 7, including disposing of removed entrained liquid by passing said liquid into the high pressure rich gas stream.

9. A method, as set forth in claim 1, including heating the first gas stream to a temperautre in the range of 550 to 650 F.

References Cited UNITED STATES PATENTS 1,523,313 1/1925 Thompson 208-310 2,771,149 11/1956 Miller et al 208-341 2,886,123 5/1959 Miller et al. 208-340 2,973,834 3/1961 Cicalese 208-340 3,238,701 3/1966 Holt 55-62 3,274,101 9/1966 West et al 208-340 3,378,992 4/1968 Pierce et al 55-62 3,477,206 1l/1969 Russell 55-62 HERBERT LEVINE, Primary Examiner U.S. Cl. X.R. 

